通過Node.js和Socket.io來實現手機的遠程控制

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用手機來實現遠程控制是不是很酷？你不需要去寫一個APP應用來實現這種功能-現在的手機瀏覽器已經支出了web socket技術，這提供了很多的可能。
這篇文章我們將用Node.js和Socket.io來實現手機控制PC的效果。

我們不必到處尋找基于HTML5的這種應用庫。我們將使用Reveal.js-它來處理幻燈片動畫效果，并支持鍵盤和觸摸事件。

我們不必自己來實現遠程控制的接口，我們將實現手機和電腦的同步。這樣不僅能控制進度，也能同步的顯示在你的手機上。

實現思路

技術上很簡單。Reveal.js讓當前的幻燈片序號在URL的hash上(e.g.http://example.com/#/1).我們將這個hash發送到所有連接的設備上，
對應的將會根據這個hash來自動的顯示響應幻燈片。這樣的話，別人可以方便的直接通過url來直接訪問到顯示的頁面，所有我們需要輸入一個驗證碼
在連接之前進行驗證。

要說的是Reveal.js已經有一套API,我們可以直接調用來同步。但是hash變化的技術很簡單，我們可以直接來實現。

運行

你可以本地運行示例，或者部署到能提供node.js環境的服務器上。本地運行更簡單些，但是必須本地有node.js并執行npm install.

運行本地代碼

• 下載示例代碼
• 確保本地已經安裝node.js。如果沒有，請安裝
• 解壓剛才下載的代碼包
• 打開終端進入相應的文件夾
• 運行npm install來安裝依賴包
• 運行node app.js來啟動應用
• PC端在瀏覽器打開http://localhost:8080，并輸入連接碼(默認是kittens)
• 在手機端瀏覽器打開http://<your computer’s local ip address>，并輸入連接碼
• 請享受

代碼

思路說完，讓我們來看看代碼。這主要涉及2個js文件-app.js服務端控制，script.js瀏覽器端。你可以運行這個應用在Node.js 1.10+或者io.js.

后端，我們用到了express和Socket.io.它主要用來響應socket.io的事件監聽。用express.static來讓public下的文件可以訪問到。
public/index.html文件保護顯示的代碼。express.static將會讓它自動顯示，所以我們不需要/來路由。

app.js

// This is the server-side file of our mobile remote controller app.
// It initializes socket.io and a new express instance.
// Start it by running 'node app.js' from your terminal.


// Creating an express server

var express = require('express'),
    app = express();

// This is needed if the app is run on heroku and other cloud providers:

var port = process.env.PORT || 8080;

// Initialize a new socket.io object. It is bound to
// the express app, which allows them to coexist.

var io = require('socket.io').listen(app.listen(port));


// App Configuration

// Make the files in the public folder available to the world
app.use(express.static(__dirname + '/public'));


// This is a secret key that prevents others from opening your presentation
// and controlling it. Change it to something that only you know.

var secret = 'kittens';

// Initialize a new socket.io application

var presentation = io.on('connection', function (socket) {

    // A new client has come online. Check the secret key and
    // emit a "granted" or "denied" message.

    socket.on('load', function(data){

        socket.emit('access', {
            access: (data.key === secret ? "granted" : "denied")
        });

    });

    // Clients send the 'slide-changed' message whenever they navigate to a new slide.

    socket.on('slide-changed', function(data){

        // Check the secret key again

        if(data.key === secret) {

            // Tell all connected clients to navigate to the new slide

            presentation.emit('navigate', {
                hash: data.hash
            });
        }
    });
});

console.log('Your presentation is running on http://localhost:' + port);

下面是前端的js文件，將監聽hashchange事件，并發送socket.io消息到服務器端。

public/assets/js/script.js

$(function() {

    // Apply a CSS filter with our blur class (see our assets/css/styles.css)

    var blurredElements = $('.homebanner, div.reveal').addClass('blur');

    // Initialize the Reveal.js library with the default config options
    // See more here https://github.com/hakimel/reveal.js#configuration

    Reveal.initialize({
        history: true        // Every slide will change the URL
    });

    // Connect to the socket

    var socket = io();

    // Variable initialization

    var form = $('form.login'),
        secretTextBox = form.find('input[type=text]');

    var key = "", animationTimeout;

    // When the page is loaded it asks you for a key and sends it to the server

    form.submit(function(e){

        e.preventDefault();

        key = secretTextBox.val().trim();

        // If there is a key, send it to the server-side
        // through the socket.io channel with a 'load' event.

        if(key.length) {
            socket.emit('load', {
                key: key
            });
        }

    });

    // The server will either grant or deny access, depending on the secret key

    socket.on('access', function(data){

        // Check if we have "granted" access.
        // If we do, we can continue with the presentation.

        if(data.access === "granted") {

            // Unblur everything
            blurredElements.removeClass('blurred');

            form.hide();

            var ignore = false;

            $(window).on('hashchange', function(){

                // Notify other clients that we have navigated to a new slide
                // by sending the "slide-changed" message to socket.io

                if(ignore){
                    // You will learn more about "ignore" in a bit
                    return;
                }

                var hash = window.location.hash;

                socket.emit('slide-changed', {
                    hash: hash,
                    key: key
                });
            });

            socket.on('navigate', function(data){

                // Another device has changed its slide. Change it in this browser, too:

                window.location.hash = data.hash;

                // The "ignore" variable stops the hash change from
                // triggering our hashchange handler above and sending
                // us into a never-ending cycle.

                ignore = true;

                setInterval(function () {
                    ignore = false;
                },100);

            });

        }
        else {

            // Wrong secret key

            clearTimeout(animationTimeout);

            // Addding the "animation" class triggers the CSS keyframe
            // animation that shakes the text input.

            secretTextBox.addClass('denied animation');

            animationTimeout = setTimeout(function(){
                secretTextBox.removeClass('animation');
            }, 1000);

            form.show();
        }

    });

});

現在是幻燈片放映時間

手機遠程訪問控制已經可以了。希望你能從中得到有趣的體驗。

參考：

http://tutorialzine.com/2015/02/smartphone-remote-control-for-presentations/
https://github.com/hakimel/reveal.js/wiki/Example-Presentations

來自：http://ljinkai.github.io/2015/06/19/phone-control-slide/